1. Technical Field
The present invention relates to an atomic cell, an atomic resonance transition device, an atomic oscillator, an electronic apparatus, and a moving object.
2. Related Art
An atomic oscillator which oscillates on the basis of energy transition of atoms of an alkali metal such as rubidium or cesium is known as an oscillator which has a high accuracy oscillation characteristic for a long period of time.
Generally, the operation principles of the atomic oscillator are largely classified into a method of using a double resonance phenomenon caused by light and microwaves, and a method of using a quantum interference effect (also referred to as coherent population trapping (CPT)) caused by two types of light beams with different wavelengths.
In an atomic oscillator of either method, typically, an alkali metal is sealed into a gas cell (atomic cell), and the gas cell is heated to a predetermined temperature by a heater in order to maintain the alkali metal in a specific gaseous state.
Here, generally, the entire alkali metal in the gas cell does not become a gas, and part of the alkali metal becomes a liquid as a surplus. Such surplus alkali metal atoms are deposited (condensed) at a location of the gas cell where a temperature is low and thus become a liquid, but shield excitation light if the surplus alkali metal atoms are present in a passing region of the excitation light, and, as a result, an oscillation characteristic of the atomic oscillator deteriorates.
Therefore, in a gas cell related to JP-A-2010-205875, a recess portion for depositing a surplus alkali metal is provided in an inner wall surface of the gas cell.
However, in the gas cell related to JP-A-2010-205875, since a surplus alkali metal which is deposited in the recess portion faces a passing region of excitation light relatively in the vicinity thereof, part of an excited gaseous alkali metal comes into contact with the surplus alkali metal in the recess portion, and thus a state of the excited gaseous alkali metal is nonuniform. As a result, there is a problem that an oscillation characteristic deteriorates (for example, a frequency varies).